全文获取类型
| 收费全文 | 937篇 |
| 免费 | 197篇 |
| 国内免费 | 185篇 |
专业分类
| 航空 | 644篇 |
| 航天技术 | 238篇 |
| 综合类 | 136篇 |
| 航天 | 301篇 |
出版年
| 2024年 | 1篇 |
| 2023年 | 11篇 |
| 2022年 | 30篇 |
| 2021年 | 29篇 |
| 2020年 | 37篇 |
| 2019年 | 31篇 |
| 2018年 | 28篇 |
| 2017年 | 19篇 |
| 2016年 | 18篇 |
| 2015年 | 28篇 |
| 2014年 | 56篇 |
| 2013年 | 56篇 |
| 2012年 | 55篇 |
| 2011年 | 85篇 |
| 2010年 | 86篇 |
| 2009年 | 76篇 |
| 2008年 | 65篇 |
| 2007年 | 61篇 |
| 2006年 | 54篇 |
| 2005年 | 47篇 |
| 2004年 | 38篇 |
| 2003年 | 30篇 |
| 2002年 | 45篇 |
| 2001年 | 35篇 |
| 2000年 | 27篇 |
| 1999年 | 40篇 |
| 1998年 | 44篇 |
| 1997年 | 36篇 |
| 1996年 | 28篇 |
| 1995年 | 18篇 |
| 1994年 | 21篇 |
| 1993年 | 20篇 |
| 1992年 | 11篇 |
| 1991年 | 11篇 |
| 1990年 | 13篇 |
| 1989年 | 10篇 |
| 1988年 | 8篇 |
| 1987年 | 5篇 |
| 1986年 | 3篇 |
| 1984年 | 1篇 |
| 1983年 | 1篇 |
| 1981年 | 1篇 |
排序方式： 共有1319条查询结果，搜索用时 125 毫秒
801.
为更好地发挥军事需求的牵引作用,将武器装备符合性质量观念提升到适用性质量观念,提高通用弹药质量水平,科学地评价通用弹药质量非常重要.分析了外军武器装备需求实现和现代质量观念,提出了面向需求的武器装备质量评价理念,论述了面向需求的武器装备质量评价的作用,研究并建立了面向需求的武器装备质量评价模型,评价模型贯彻了需求牵引的思想.通过对通用弹药的特点和基本需求分析,建立了科学的、系统的通用弹药质量评价指标体系. 相似文献
802.
文章以武器装备体系(Weapon System-of-Systems,WSoS)发展论证需求为牵引,结合现代战争复杂电磁环境下武器装备体系特点,综合考虑武器装备体系效能评估方法,采用我国原创的可拓学理论,从定性与定量两个角度对武器装备体系效能进行评估,结合层次分析法、Delphi法,建立武器装备体系效能评估模型,利用Matlab进行实例仿真实验,表明该方法能够根据隶属等级对武器装备体系效能进行评估,并可分析得出二级指标的弱项,对各指标的优化具有指导作用。 相似文献
803.
804.
805.
S. Savin L. Zelenyi N. Maynard I. Sandahl H. Kawano C. T. Russell S. Romanov E. Amata L. Avanov J. Blecki J. Buechner G. Consolini G. Gustafsson S. Klimov F. Marcucci Z. Nemecek B. Nikutowski J. Pickett J. L. Rauch J. Safrankova A. Skalsky V. Smirnov K. Stasiewicz P. Song J. G. Trotignon Yu. Yermolaev 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2002,30(12):2821-2830
Multi-spacecraft tracing of the high latitude magnetopause (MP) and boundary layers and Interball-1 statistics indicate that:
- 1. (a) The turbulent boundary layer (TBL) is a persistent feature in the region of the cusp and ‘sash’, a noticeable part of the disturbances weakly depends on the interplanetary magnetic field By component; TBL is a major site for magnetosheath (MSH) plasma penetration inside the magnetosphere through percolation and local reconnection.
- 2. (b) The TBL disturbances are mainly inherent with the characteristic kinked double-slope spectra and, most probably, 3-wave cascading. The bi-spectral phase coupling indicates self-organization of the TBL as the entire region with features of the non-equilibrium multi-scale and multi-phase system in the near-critical state.
- 3. (c) We've found the different outer cusp topologies in summer/winter periods: the summer cusp throat is open for the decelerated MSH flows, the winter one is closed by the distant MP with a large-scale (several Re) diamagnetic ‘plasma ball’ inside the MP; the ‘ball’ is filled from MSH through patchy merging rather than large-scale reconnection.
- 4. (d) A mechanism for the energy release and mass inflow is the local TBL reconnection, which operates at the larger scales for the average anti-parallel fields and at the smaller scales for the nonlinear fluctuating fields; the latter is operative throughout the TBL. The remote from TBL anti-parallel reconnection seems to happen independently.
References
Chen, J., Fritz, T.A., Sheldon, R.B., Spencer, H.E., Spjeldvik, W.N. et al., 1997. Temporary confined population in the polar cap during the August 27, 1996 geomagnetic field distortion period. Geophys. Res. Lett. 24, p. 1447. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (51)
Chen, J. and Fritz, T.A., 1998. Correlation of cusp MeV helium with turbulent ULF power spectra and its implications. Geophys. Res. Lett. 25, p. 4113. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (34)
Consolini, G. and Lui, A.T., 2000. Symmetry breaking and nonlinear wave-wave interaction in current disruption: possible evidence for a phase transition. In: Magnetospheric Current SystemsGeophysical Monograph 118, American Geophysical Union, Washington D.C., pp. 395–401.
Dubinin, E., Skalsky, A., Song, P., Savin, S., Kozyra, J. et al., 2001. Polar-Interball coordinated observations of plasma characteristics in the region of the northern and southern distant cusps. J. Geophys. Res. accepted .
Fedorov, A., Dubinin, E., Song, P., Budnick, E., Larson, P. and Sauvaud, J.A., 2000. Characteristics of the exterior cusp for steady southward IMF: Interball observations. J. Geophys. Res. 105, pp. 15,945–15,957.
Fritz, T.A., Chen, J. and Sheldon, R.B., 2000. The role of the cusp as a source for magnetospheric particles: a new paradigm?. Adv. Space Res. 25, pp. 1445–1457. Article | PDF (871 K)
| View Record in Scopus | Cited By in Scopus (18)
Haerendel, G. and Paschmann, G., 1975. Entry of solar wind plasma into the magnetosphere. In: Hultqvist, B. and Stenflo, L., Editors, 1975. Physics of the Hot Plasma in the Magnetosphere, Plenum, NY, p. 23.
Haerendel, G., 1978. Microscopic plasma processes related to reconnection. J. Atmos. Terr. Phys. 40, pp. 343–353. Abstract | PDF (1141 K)
| View Record in Scopus | Cited By in Scopus (27)
Klimov, S. et al., 1997. ASPI Experiment: Measurements of Fields and Waves Onboard the INTERBALL-1 Spacecraft. Ann. Geophys. 15, pp. 514–527. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (88)
Kuznetsova, M.M. and Zelenyi, L.M., 1990. The theory of FTE: Stochastic percolation model. In: Russell, C.T., Priest, E.R. and Lee, L.C., Editors, 1990. Physics of Magnetic Flux RopesAmerican Geophysical Union, pp. 473–488.
La Belle-Hamer, A.L., Otto, A. and Lee, L.C., 1995. Magnetic reconnection in the presence of sheared flow and density asymmetry: application to the Earth's magnetopause. J. Geophys. Res. 100, pp. 11,875–11,889.
Lagoutte, D., Lefeuvre, F. and Hanasz, J., 1989. Application of bi-coherence analysis in study of wave interactions in space plasma. J. Geophys. Res. 94, p. 435. Full Text via CrossRef
Maynard, N.C., Savin, S., Erickson, G.A., Kawano, H. et al., 2001. Observations of fluxes of magnetosheath origin by Polar and Interball at high latitudes behind the terminator-relationships to the magnetospheric “sash”. J. Geophys. Res. 104, pp. 6097–6122. Full Text via CrossRef
Merka, J., Safrankova, J., Nemecek, Z., Fedorov, A., Borodkova, N., Savin, S. and Skalsky, A., 2000. High altitude cusp: Interball observations. Adv. Space Res. 25, pp. 1425–1434. Article | PDF (915 K)
| View Record in Scopus | Cited By in Scopus (22)
Onsager, T.G., Scudder, J., Lockwood, M. and Russell, C.T., 2001. Reconnection at the high latitude magnetopause during northward IMF conditions. J. Geophys. Res. 106, pp. 25,467–25,488.
Romanov, V., Savin, S., Klimov, S., Romanov, S., Yermolaev, Yu., Blecki, J. and Wronowski, R., 1999. Magnetic turbulence at the magnetopause: plasma penetration. J. Tech. Phys. (Poland) 40 1, pp. 329–332.
Safrankova, J., Nemecek, Z., Prech, L., Sauvaud, J.-A. and Wing, S., 2001. The structure of the magnetopause layers at magnetospheric flanks. In: Proceedings of COSPAR/ESA, Colloquium.
Sagdeev, R.Z. and Galeev, A.A., 1969. Nonlinear plasma theory. In: , Benjamin, White Plains, N.Y., p. 6.
Sandahl, I., Popielavska, B., Budnick, E.Yu., Fedorov, A., Savin, S., Safrankova, J. and Nemecek, Z., 2000. The cusp as seen from Interball. In: Proceedings of Cluster II Workshop. Multiscale/Multipoint Plasma MeasurementsESA/SP-499, Imperial College, London, pp. 39–45.
Savin, S.P., Romanov, S.A., Fedorov, A.O., Zelenyi, L., Klimov, S.I. et al., 1998. The cusp/magnetosheath interface on May 29, 1996: Interball-1 and Polar observations. Geoph. Res. Lett. 25, pp. 2963–2966. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (23)
Savin, S.P., Borodkova, N.L., Budnik, E.Yu., Fedorov, A.O., Klimov, S.I. et al., 1998. Interball tail probe measurements in outer cusp and boundary layers. In: Horwitz, J.L., Gallagher, D.L. and Peterson, W.K., Editors, 1998. Geospace Mass and Energy Flow: Results from the International Solar-Terrestrial Physics ProgramGeophysical Monograph 104, American Geophysical Union, Washington, D.C., pp. 25–44.
Savin, S., Zelenyi, L., Budnik, L., Borodkova, N., Fedorov, A. et al., 1998. Manifestations of Boundary Layer Dynamics in Substrom Activity. Multi Spacecraft Study. In: Kokubun, S. and Kamide, Y., Editors, 1998. SUBSTORM-4, ‘Conf. on Substorms-4’Lake Hamana, Japan: March 9–13, 1998, , Terra Scientific Publ. Co., Tokyo, pp. 125–130.
Savin, S., Budnik, E., Nozdrachev, M., Romanov, V. et al., 1999. On the plasma turbulence and transport at the polar cusp outer border. Chekhoslovak J. Phys. 49 4a, pp. 679–693. View Record in Scopus | Cited By in Scopus (15)
Savin, S., Skalsky, A., Romanov, S., Budnick, E., Borodkova, N., Zelenyi, L. et al., 2000. Outer cusp boundary layer: summer/winter assymetry. In: Proceedings of Symposium ‘From solar corona through interplanetary space into magnetosphere and ionosphere’, Kyiv University, Kyiv, pp. 229–232.
Savin, S., Blecki, J., Pissarenko, N., Lutsenko, V., Kirpichev, I. et al., 2002. Accelerated particles from turbulent boundary layer. In: Proc. of Interball/COSPAR Colloquium ‘Acceleration And Heating In The Magnetosphere’ in press .
Savin, S., Maynard, N., Sandahl, I., Kawano, H., Russell, C.T., Romanov, S., Zelenyi, L. et al., 2002. Magnetosheath/Cusp Interface. Ann. Geophys. submitted .
Siscoe, G.L., Erickson, G.M., Sonnerup, B.U.Ö., Maynard, N.C., Siebert, K.D., Weimer, D.R. and White, W.W., 2001. Magnetospheric sash dependence on IMF direction. Geophys. Res. Lett. in press .
Spreiter, J.R. and Briggs, B.R., 1962. Theoretical determination of the form of the boundary of the solar corpuscular stream produced by interaction with the magnetic dipole field of the Earth. J. Geophys. Res. 67, pp. 37–51. Full Text via CrossRef
Zelenyi, L.M. and Milovanov, A.V., 1998. Multiscale magnetic structure of the distant tail: self-consistent fractal approach. In: New Perspectives on the Earth MagnetotailGeophys. Monograph 105, AGU, Washington DC, pp. 321–338.
相似文献
806.
A self-consistent time-dependent, two-dimensional MHD model with a realistic energy equation is developed to understand the origin of bright coronal emission accompanying the occurrence of a new bipolar magnetic region. The motivation for this study is the interpretation of anticipated observations to be made by the SOHO mission.Purple Mt. Obser., PRC 相似文献
807.
通过对网络广告发展的现状和问题分析及网络广告策划方法探讨，提出了提高网络广告策划质量的新思路。 相似文献
808.
给出了一类解耦非线性控制系统稳定跟踪设定线性系统的建议性解法。简单讨论了不同反馈解耦问题的区别，解耦系统极点配置的条件和解耦后的非线性系统保证稳定性的一种途径，并且给出了所用的方法适用的范围和一个建议性判据。 相似文献
809.
介绍了一种预示固体发动机火箭压强曲线上升段的实用方法。用该方法编制的程序具有结构简单,精度高的优点,能够满足工程需要。 相似文献
810.
空间监测数据表明,太阳系内空间微粒较多,大于1厘米的碎粒每平方米每年碰到1个的概率为10-6(见图1)。为防止与小行星或彗星相撞,飞船上应装有预警雷达,预先发现和改变轨道,避免直接碰撞。当飞出小行星带(5天文单位)和凯珀带(500天文单位)以后,这种撞击概率比过去估计的要小得多 相似文献